Process for determining the quantity of potassium in fertilizers



Patented July 19, 1932 .onirsn STATES PATENT OFFICE EUGENE I1. PARKER, OF MOUNT PLEASANT, TENNESSEE PROCESS FOR DETERMINING THE QUANTITY OF POTASSIUM IN FERTILIZERS No Drawing.

This invention relates to a process for determining the quantity of potassium in fertilizers. It has been proposed to employ a process for determining the quantity of rials and in which the calcium, iron, alumi num -and lead salts are precipitated or re'- moved from the solutions contalning the potassiumsalt. i

1'20 Afurther object of the invention is the provision of a process for determining a quantity of potassium in a given sample 'ofa mixed fertilizer by forming hydroxides ofthe aluminum, calcium, iron and lead salts found in the fertilizer-and'then re-acting a sulphide with the solution containing hydroxides so thatwhen a soluble oxalate is applied to the solution,the' sulphides of aluminum, iron, lead and calcium will be prej'ao cipitated and. removed from the solution which is evaporated to approximate dryness and then treated with sulphuric acid and further evaporated to dryness to obtain potassium sulphate. This sulphate is maintained ata red heat until the sulphate becomes white after which it is dissolved in water andto this solution is added a few drops of hydrochloric acid together with platinic chloride in excess, the resultant product being potass ium platinic chloride from which it is possible to determine readilythequantityof potassium contained originally in the sample of the fertilizer. V

Theinvention will be best understood from r a consideration of the, following detailed description; nevertheless it is to be understood that theinvention is not confined to the disclosure, being susceptible of such changes and modifications which shall define no mate- 5 rial departure'from the salient features of Application filed March 26, 1931. Serial No. 525,624.

the invention as expressed in the appended claims.

In carrying out my invention it is essential to carefully prepare certain re-agents, such asdammonium chloride and platinum chlor1 e. i The ammonium chloride is prepared by dissolving 100 grams of ammonium chloride in 500 cubic centimeters of water to which is added from 5 to grams of pulverized potassium-platinic chloride. This solution is agitated at intervals from 6 to 8 hours. It is then allowed to settle over night after which it is filtered. The residue obtained may be used for the preparation of a fresh supply. The solution itself is approximately a solution of ammonium chloride and a saturated solution of vpotassium platinic chloride. Such a solution will not dissolve any more potassium platinic chloride but will dissolve water soluble, sodium and magnesium sa ts.

A platinum solution is made by dissolving 2 th grams of platinic chloride in 10 cubic centimeters measures of Water. The platinic chloride is obtained by dissolving metallic platinum in aqua regia consisting of 82 parts of hydro-chloric acid and 18 parts of nitric acid. The resultant product which is platinic chloride is evaporated to dryness and then '80 dissolved in hydrochloric acid and then evaporated to dryness to eliminate any nitrates that may be present.

A third reeagent which is an important feature of the present process is either ammonium sulphide or hydrogen sulphide. The ammonium sulphide is produced by saturating 500 cubic centimeters of ammonium hydroxide having a specific gravity of 0.945, with hydrogen sulphide. The hydrogen sulphide gas is passed through the solution of ammonium hydroxide.

It is necessary to specially prepare the mixed fertilizers before applying re-agents.

In order to accomplish the proper results 10 monium sulphide solution described above is thoroughly shaken with the solution of the fertilizer, or hydrogen sulphide gas may be passed through the alkaline solution until saturation takes place and all of the soluble salts of aluminum, iron and lead will be precipitated as sulphides. Powdered am- ,monium oxalate is added to --'the solution which will precipitate all of the lime present as calcium oxalate and-since the. sulphidesof aluminum, iron and lead are insoluble in the through a dry filter to ammonium oxalatesolu-tion, the sulphides will be precipitated. This solution containing the precipitate is allowed tofcool and diluted to 500 cubic centimeters with water, mixed thoroughly after which it is passed remove the calcium oxalate and sulphides.

I When itis desired to determine the total amount of potassium in organic substances,

' such as cottonseedmeal, tobacco stems, etc,

I saturate 10 grams of the substance with.

strong sulphuric acid and ignite the samein j a muflie furnace at low red heat to destroy organic matter. The potash salts left in the residueare converted into sulphate which is not volatile, A small quantity of strong hydro-chloric acid is added and this productis warmed slightly inorder to'loosen the mass from the dish or crucible, after which the mass is transferred to a flask approximately 500 cubic centimeters.- Water is added to the mass and thes'ame isboiled for minutes. This solution ismade alkaline by addition'of sufiicient ammonium: -'l'1 ydroxide. 15 cubic centimeters of ammonium sulphide solution I is added to the solution of the'flask or'the.

solution issaturatecl with hydrogen sulphide and when the solution is thoroughly shaken the ammonium' sulphide. or the hydrogen sulphide will precipitate. all of the soluble salts of aluminum, iron, an'd'lead as sulphides from the alkaline solution. Powdered ammonlum oxalate 1s added in sufiicient quantie ties to precipitate all of the "lime present.

' The sulphides being insoluble in the oxalate solution will'remain as precipitate. This solution is cooled and then diluted with water sothat the solution will beapprox mately 500 cubic centimeters which is mixed thoroughly 7 thenpassed through a: dry filter.

1 ness to form a powder to which is added one cubic centimeter of diluted sulphuric acid cubic centimeters of the solution thus obtained is evaporated to approximate dry- (one part of sulphuric acid to one part of water); This is evaporated to dryness and ignited .until the product becomes white.

The product thus obtained is potassium sulphate which being non-volatile may be maintain'edat a full redheat until'the residue is perfectly white. 7 The residue is dissolved in hot water using at least 20 cubic centimeters,

1 few drops of hydrochloric acid and the r0135 deCi-grams of potassium'sulphate. A

platinic chloride solution noted above is added in excess. The product thus obtained is evaporated on a water bath until a thick paste is obtained which is treated with 80% alcohol, specific gravity 0.8645. At this time care must be exercised to avoid the absorption of ammonia. The product is washed thoroughly with 80% alcohol both by decantation and on the filter. The washing is continued after the filtrate is colorless. The filtrate then'is washed with 10 cubic centimeters of the ammonium chloride-solution noted above to remove impurities, such as water soluble sodium and magnesium salts from the precipitate. The washing is continued five or six times after which it is thoroughly washed with 80% alcohol and dried for 30 minutes hydroxides into sulphides,adding ammonium oxalate to cause precipitation of the'su lphides and any lime present,-filteringsaid solution to remove the precipitate,evaporating =50 cubiccentimetersof the filtered solution to approximate dryness, adding one cubic centimeter-ofdilutesulphuric acid to the evaporate-to formpotassiumsulphate,heating said sulphate until the same becomes white in color, dissolvingthesulphate in hot water, then adding a few drops of hydrochloric acid 7 and. a solution of platinic chloride in excess to formp'otassium; ing wlth'water and'alcoh'ol. a c -2. The'process of determining the quanplatinic chloride,- lixiyiattity of potassium in fertilizers which com prisesboiling a sample of the fertilizer in water, re-acting ammonium hydroxide with the hot solution for converting iron, aluminum and lead salts found in the fertilizer into their respectivahydroxides,reacting a sulphide with theTSOllltlOn' for converting the hydroxldes of-the'elements into sulphides,

precipitating the'lsulphide's with ammonium oxalate, removing the precipitate, evaporating the filtered solution to approximately a dry powder, reacting the dry powder. with a dilute solution ;of sulphuric'acid to form POiSa-SSIIHIL sulphate, heating'the sulphate and adding hydrochloricacid and a solutio'n of platinic' chloride in excess, then 'lixiviating the product with water andfalcohol.

Y A'method of re noving calcium, lead,

iron and aluminum salts from a sample of fertilizer which. comprises converting said sa-lts inj a. solution into' hydroxides by ammonium hydroxide and then adding aminonium sulphide and precipitating the sulphides of calcium, lead, iron and aluminum with ammonium oxalate, then removing the precipi-- tate from the solution.

5 4. A method of removing calcium, lead, iron and aluminum salts from a sample of fertilizer which comprises converting said salts in a solution into hydroxides by ammonium hydroxide and then adding ammonium sulphide and precipitating the sulphides of calcium, lead, and iron and aluminum with ammonium oxalate, then removing the precipitate from the solution, evaporating the filtrated solution to dryness to obtain a potassium salt, re-acting this salt with sulphuric acid to obtain potassium sulphate, re-acting with the sulphate, a few drops of hydrochloric acid and an excess of platinic chloride solution, lixiviating the product with water 20 and alcohol.

EUGENE L. PARKER. 

